Abstract: Based on the similarity theory, the interaction of fluid flow and gas flow in gas-liquid two-phase flow and the expansion of argon in actual continuous casting were taken into account, and the relation between argon flow rate in a plant and gas flow rate in experiment was established by modified Froude numbers. The transformation formulas of flow rate between four kinds of simulation gases and argon in a plant were obtained. A 0.6:1 scale water model was undertaken to simulate the technological process in a prototype with the cross section of 210 mm×900 mm. The results show that the experimental phenomena agree well with the practical ones. When the water flow rate is 3.80 m³·h^-1 and the gas flow rate is 0.93 L·min^-1 in modeling, bubbles do not lead to excessive level fluctuation due to their relatively homogeneous dispersion in the mold. When the water flow rate is 3.80 m³·h^-1 and the gas flow rate is 2.79 L·min^-1, most bubbles float up in the vicinity of the submerged entry nozzle and there is strong fluctuation around the submerged entry nozzle, so opening of slag layers occurs in the mold. The correctness of similarity transformation of gas flow rate was validated with consistencies between simulation results and practical phenomena.